disorder of arousal; lack of awareness; impaired consciousness

Classification

• lethargy
• obtundation
• stupor
• coma

* also see sleep, drowsiness

Etiology

• bilateral impairment of cerebral hemisphere function
• failure of the brain stem reticular-activating system
• structural lesions
  • supratentorial lesions
    • encroaching on or compressing diencephalic structures such as the thalamus
    • rapidly exapnding masses
      • malignant tumors
      • abscesses
      • hematomas
      • infarction with edema
  • infratentorial lesions
    • direct involvement or compression of the reticular activating system by an adjacent lesion (i.e. cerebellar mass)
    • infarction
    • hemorrhage
    • demyelination
    • infection
    • neoplasm
• central pontine myelinolysis
• toxic & metabolic abnormalities
  • most frequent cause of coma
  • more likely to cause coma in a patient with previous brain injury
• multifocal involvement of the central nervous system
  • cerebral vasculitis
  • encephalitis
  • subarachnoid hemorrhage
  • adrenoleukodystrophy
• status epilepticus, especially non-convulsive
• sagittal sinus thrombosis

Laboratory

• basic chemistry panel
• complete blood count (CBC)
• lumbar puncture/CSF analysis (after CT of the head)
• electroencephalography
  • non-convulsive status epilepticus
  • hepatic encephalopathy
  • Herpes simplex encephalitis
  • locked-in syndrome
  • catatonia
  • brain death

Radiology

• computed tomography (CT) of the head

Differential diagnosis

• psychogenic unresponsiveness
  • uncommon
  • patient may appear unable to respond to environment despite normal function of the reticular activating system & cerebral hemispheres
  • conversion disorder
  • malingering
  • fugue state
  • catatonic schizophrenia
  • severe depression
• abulia
• locked-in syndrome
• persistent vegetative state

Management

(also see coma)

• reversal of identifiable causes
• reduction of increased intracranial pressure

More general terms

• disease/disorder primarily affecting brain

More specific terms

• coma
• lethargy
• loss of consciousness (LOC)
• minimally conscious state
• obtundation
• persistent vegetative state
• stupor

Additional terms

• abulia
• altered state of consciousness
• arousal
• arousal symptom
• Glasgow coma scale (GCS)
• locked-in syndrome; cognitive-motor dissociation
• sleep